Microwave dielectrics in Ca(5-x)A(x)Nb(2)TiO(12) (A = Mg, Zn) system have been prepared for different values of x by conventional solid-state ceramic route. The elastic properties of the ceramics were investigated as a function of composition by ultrasonic techniques. X-ray diffraction studies revealed that the ceramics form phase pure compounds for 0 <= x <= 1and form mixture phases beyond x = 1. The elastic properties were strongly affected by structural transformations. Magnesium-based compositions have better elastic properties compared with zinc-based system. (c) 2005 Elsevier Ltd. All rights reserved.